1. Field of the Invention
The present invention relates generally to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves an undersea hydraulic coupling member that is capable of holding higher pressures at increased flow rates without increasing the external dimensions or weight.
2. Description of Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member, with soft seals positioned within the female member to seal the junction between the male and the female members. The female member is generally a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains soft seals and receives the male portion of the coupling. The male member includes a cylindrical portion, or probe, at one end having a diameter approximately equal to the diameter of the large bore of the female portion of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to the various embodiments of the device, the soft seals, or O-rings, either abut the end or face of the male member or engage the cylindrical probe wall about its outer circumference. The hydraulic fluid is then free to flow through the female and male members of the coupling and seals prevent that flow from escaping about the joint and the coupling. A check or poppet valve may be installed in the female member and also in the male member. Each valve closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is a part.
In U.S. Pat. No. 4,694,859 to Robert E. Smith, III, assigned to National Coupling Company, Inc., of Stafford, Tex., an undersea hydraulic coupling and metal seal is disclosed. This patent describes a reusable metal seal which engages the outer circumference of the probe when it is positioned within the female member bore. The metal seal is held in place by a retainer. When the male and female portions of the coupling are parted under pressure, the retainer prevents the metal seal from blowing out through the bore of the female member. The male and female members each have valve actuators extending from the poppet valves. When the male member enters the female member bore and the valve actuators are engaged, each of the poppet valves is urged opened and the poppet valve springs arc compressed. U.S. Pat. No. 5,762,106 to Robert E. Smith, III, assigned to National Coupling Company, Inc., also shows an undersea hydraulic coupling and radial metal seal that engages the diameter of the probe or male member.
U.S. Pat. No. 4,900,071 to Robert E. Smith, III, assigned to National Coupling Company, Inc., shows an undersea hydraulic coupling with a two-piece retainer for restraining radial movement of a wedge-shaped annular seal into the central bore of the female member. The annular seal is restrained by a dove tail interfit with a mating shoulder on either the retainer sleeve, the retainer-locking member, or both parts. U.S. Pat. No. 5,052,439 also shows an undersea hydraulic coupling with a two-piece retainer having a dovetail interfit with an annular seal.
U.S. Pat. No. 5,390,702 to Robert E. Smith, III, assigned to National Coupling Company, Inc., shows an undersea hydraulic coupling having a male member with a stepped outer body to more accurately position and guide the male member into the seals, ensuring greater seal reliability and longer seal life. These step surfaces also help prevent implosion of the seals due to sea pressure when the end of the male member comes out of the seals.
Additionally, U.S. patent application Ser. No. 09/293,554 to Robert E. Smith, III, assigned to National Coupling Company, Inc., relates to an undersea hydraulic coupling having an extended probe section having a valve spring with a greater diameter then the diameter of the extended probe section, to provide sufficient forces to prevent the poppet valve of the male member from opening at high subsea pressures, and to reduce the diameter of the sealing surface.
In subsea hydraulic systems, it is desirable to increase flow rates through the system of which the couplings are a part. The flow rate through the coupling, and the lines attached to the coupling, are a function of the diameter of the internal bore through the coupling and lines. As known by those skilled in the art, the maximum flow coefficient through a coupling may be determined and calculated based on the dimensions of the coupling bore.
To withstand the higher pressures of hydraulic flow through a coupling, the body of the coupling member, and the probe section of the male member in particular, must be of sufficient thickness to withstand the internal working pressure and the pressure external to the coupler as a result of substantial ocean depths. Accordingly, as known by those skilled in the art, the metal thickness of the coupling body may be determined by the working pressure through the bore of the coupler, and the yield of the material from which the coupling is machined. However, increasing the size and thickness of the coupling member to accommodate higher working pressures and higher subsea pressures is problematic. Remote operating vehicles (ROVs) must frequently be used to transport, engage and disengage coupling members. The ROVs may be limited in weight and size capacity to transport and install coupling members. Frequently, multiple coupling members are connected to a manifold plate and must be transported and mated while subsea with couplings attached to an opposing manifold plate. To enable the remote operating vehicle to accomplish this work, it is desirable to minimize the size and weight of each coupling member. In the past, reducing the size and weight of the coupling member also requires reducing the flow rate or the capability of the coupling to handle higher pressures.